The present invention relates to apparatus for separating an inner mold from a cylindrical molding, e.g. a cylindrical rubber molding, which sticks to the outer circumference of the inner mold.
In the production process of rubber belts, for example, a cylindrical unvulcanized belt material is wound over an inner mold and is vulcanized in a vulcanizer. After vulcanization, the inner mold to which the vulcanized cylindrical rubber molding (called a slab) adheres is ejected by a mold ejecting apparatus to recover the rubber molding. The conventional mold ejecting apparatus has the construction illustrated in FIG. 6, and includes a mold ejecting ring body 61 having a bore corresponding to the outer diameter of an inner mold 62 which is placed directly above a central opening 64 of a frame base 63. The bottom end face of the cylindrical rubber molding A which is formed on and sticks to the outer circumference of the inner mold 62 is matched with the ring body 61 so as to place the cylindrical rubber molding A, together with the inner mold 62, on the ring body 61. Directly above the center of the ring body 61, a piston rod 66 of a hydraulic cylinder unit 65 is arranged to be moved downwardly. The piston rod 66 is arranged to push the inner mold 62 downwardly relative to the cylindrical rubber molding A and eject the inner molding 62 from the molding A.
Although not illustrated, there are also reverse arrangements wherein the inner mold is fixed in the specified position on the frame base, and a ring body matched with the upper end face of a cylindrical rubber molding is pushed down by a piston rod of a hydraulic cylinder unit to eject the inner mold. In both cases, the conventional mold ejecting apparatus uses a fixed-form ring body 61 matched to the size of the inner mold 62 to eject the inner mold 62 from the molding A.
In the above-mentioned conventional mold ejecting apparatus, when the size of the inner mold is changed, the ring body must also be replaced with one that matches the size of the inner mold, and the replacement is normally made by operators who select an appropriate ring body from many ring bodies. As the exchange of ring bodies takes much time, the work efficiency is low. Furthermore, since the inner mold is ejected when the inner circumference of the cylindrical rubber molding is in close contact with the outer circumference of the inner mold it is necessary to apply a very large pressing force (ejecting force) of the piston rod of the cylinder unit against the inner mold or the ring body. Hence the ring body tends to break, and the inner mold may be damaged if the inner mold is not set properly. The cylindrical rubber molding may be damaged or deformed by similar causes.